I'm a long-time user of free/open source software, and write various things for both fun and profit. I don't take myself all that seriously and I do all of my own stunts.
You can find me at these fine establishments on the web: Open Source Musings, The Monday Kickoff, Weekly Musings. and The Plain Text Project.
Authored Comments
Some of those projects look really interesting, especially the UNESCO Thesaurus. It'll be interesting to watch how all of this develops and spreads.
It's whatever you're most comfortable with, and to be honest I'm very comfortable with LibreOffice Writer. And I think the EPUB conversion extension (which I used a few times with OOO Writer) work with LO Writer.